1. Field of the Invention
The present invention relates to a solid-fuel burner for burning solid fuels and a combustion method by using the burner. The burner according to the present invention is specifically suitable for the use as a single-stage combustion burner which can be relied on alone for the complete combustion of solid fuels.
2. Prior Art
Solid-fuel burners designed for burning solid fuels such as coal particle are required to reduce the concentration of nitrogen oxide (hereinafter, called as Nox). To meet this requirement, low-NOx burners that create a decrease-NOx reaction in the flame have been developed. In these low-NOx burners, by introducing fuels into the flame, which lacks oxygen and its temperature is high, nitrogen contents contained in the fuel are changed into deoxidization materials, such as ammonia or cyanogen, and discharged, thereby reducing NOx to nitrogen. In a low-NOx burner, it is necessary to create a deoxidization flame, which lacks oxygen and its temperature is high, near the burner. For this reason, various proposals have been made so as not to mix fuel with air near the burner. For example, a technology has been proposed wherein the end portion of the partition wall that separates the outermost circumferential air nozzle from the inner air nozzle is designed to be a pipe expanding structure so that air flowing through the outermost circumferential air nozzle can be injected in the direction of the outer circumference (for example, see patent document 1).
[Patent document 1] Japanese Patent Publication No. 3344694 (claim 1, FIG. 1)